Table_1_Aroma profiles of sweet cherry juice fermented by different lactic acid bacteria determined through integrated analysis of electronic nose and gas chromatography–ion mobility spectrometry.DOCX

Sweet cherries are popular among consumers, with a recent explosion in sweet cherry production in China. However, the fragility of these fruits poses a challenge for expanding production and transport. With the aim of expanding the product categories of sweet cherries that can bypass these challenges, in this study, we prepared sweet cherry juice fermented by three different lactic acid bacteria (LAB; Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus GG), and evaluated the growth, physiochemical, and aroma characteristics. All three strains exhibited excellent growth potential in the sweet cherry juice; however, Lactobacillus acidophilus and Lactobacillus plantarum demonstrated more robust acid production capacity and higher microbial viability than Lactobacillus rhamnosus GG. Lactic acid was the primary fermentation product, and malic acid was significantly metabolized by LAB, indicating a transition in microbial metabolism from using carbohydrates to organic acids. The aroma profile was identified through integrated analysis of electronic nose (E-nose) and headspace gas chromatography–ion mobility spectrometry (HS-GC–IMS) data. A total of 50 volatile compounds characterized the aromatic profiles of the fermented juices by HS-GC–IMS. The flavor of sweet cherry juice changed after LAB fermentation and the fruity odor decreased overall. Lactobacillus acidophilus and Lactobacillus plantarum significantly increased 2-heptanone, ethyl acetate, and acetone contents, bringing about a creamy and rummy-like favor, whereas Lactobacillus rhamnosus GG significantly increased 2-heptanone, 3-hydroxybutan-2-one, and 2-pentanone contents, generating cheesy and buttery-like odors. Principal component analysis of GC–IMS data and linear discriminant analysis of E-nose results could effectively differentiate non-fermented sweet cherry juice and the sweet cherry juice separately inoculated with different LAB strains. Furthermore, there was a high correlation between the E-nose and GC–IMS results, providing a theoretical basis to identify different sweet cherry juice formulations and appropriate starter culture selection for fermentation. This study enables more extensive utilization of sweet cherry in the food industry and helps to improve the flavor of sweet cherry products.

甜樱桃深受消费者喜爱，近年来中国甜樱桃产量激增。然而，这些水果的脆弱性给扩大生产和运输带来了挑战。本研究旨在拓展能够克服这些挑战的甜樱桃产品类别，我们制备了由三种不同的乳酸菌（LAB；乳酸杆菌、植物乳杆菌和鼠李糖乳杆菌GG）发酵的甜樱桃汁，并评估了其生长、生理化学和香气特征。所有三种菌株在甜樱桃汁中均表现出优异的生长潜力；然而，乳酸杆菌和植物乳杆菌显示出比鼠李糖乳杆菌GG更强的酸产生能力和更高的微生物存活率。乳酸是主要的发酵产物，而苹果酸被乳酸菌显著代谢，表明微生物代谢从碳水化合物利用向有机酸利用的转变。香气特征通过电子鼻（E-nose）和顶空气相色谱-离子迁移谱（HS-GC-IMS）数据的综合分析得以识别。HS-GC-IMS共鉴定出50种挥发性化合物，这些化合物构成了发酵果汁的香气特征。乳酸菌发酵后，甜樱桃汁的风味发生了变化，果香总体上有所降低。乳酸杆菌和植物乳杆菌显著增加了庚酮、乙酸乙酯和丙酮的含量，带来了奶油和酒香般的味道，而鼠李糖乳杆菌GG显著增加了庚酮、3-羟基丁-2-酮和戊酮的含量，产生了奶酪和黄油般的气味。GC-IMS数据的主成分分析和电子鼻结果的线性判别分析能够有效区分未发酵的甜樱桃汁和分别接种不同LAB菌株的甜樱桃汁。此外，电子鼻和GC-IMS结果之间存在高度相关性，为识别不同的甜樱桃果汁配方和发酵的适宜启动菌种选择提供了理论基础。本研究使得甜樱桃在食品工业中的广泛应用成为可能，并有助于提升甜樱桃产品的风味。